Answer
Please see the work below.
Work Step by Step
We know that $HCN$ is the weakest acid
$K_a$ of $4.9\times 10^{-10}$ is less than $K_a$ of $1.7\times 10^{-15}$ of $HC_2H_3O_2$ and $HClO_4$ is a strong acid.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.